This disclosure relates to a method and system for estimating petrophysical quantities for a wide range of water salinity values in a subsurface formation.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as an admission of any kind.
Wells are generally drilled into a surface (land-based) location or ocean bed to recover natural deposits of oil and natural gas, as well as other natural resources that are trapped in geological formations. A well may be drilled using a drill bit attached to the lower end of a “drill string,” which includes a drill-pipe, a bottom hole assembly, and other components that facilitate turning the drill bit to create a borehole. For oil and gas exploration and/or monitoring, it may be desirable to obtain information about the subsurface formations that are penetrated by a borehole for analysis. More specifically, this may include obtaining downhole measurements and estimating petrophysical quantities, such as water-filled porosity, water salinity, and/or water phase tortuosity, of the subsurface formations.
In some instances, dielectric measurements are obtained by a downhole tool and used to estimate the petrophysical quantities. However, many processes that are used to estimate the petrophysical quantities suffer from certain difficulties. For example, many processes that use the dielectric measurements alone may not solve for the water salinity when the salinity has values that are medium to high.